INTERNAL Acknowledge AGW is real and human-caused (EP1,2,3) Doubt AGW is real and human-caused (EP4b-1,2) 1979 ‘The most widely held theory is that:—The increase [in atmospheric CO2] is due to fossil fuel [82] combustion;—Increasing CO2 concentration will cause a warming of the earth’s surface;—The present trend of fossil fuel consumption will cause dramatic environmental effects before the year 2050.’ 1982 ‘The question of which predictions and which models best simulate a carbon dioxide induced climate [83] change is still being debated by the scientific community. Our best estimate is that doubling of the current concentration could increase average global temperature by about 1.3° to 3.1 °C . . . .’ 1982 ‘There is currently no unambiguous scientific evidence that the earth is warming. If the earth is on a [83] warming trend, we’re not likely to detect it before 1995.’a PEERREVIEWED 1996 [76] 1995 [86] NON-PEERREVIEWED 1981 ‘The conviction in the scientific community that the observed trend of increasing carbon dioxide, if it [87] continues, will cause a global warming is based on a variety of theoretical studies . . . the results are now fairly consistent. For a carbon dioxide doubling the calculated mean surface-air temperature increase is approximately 2 °C to 3 °C. The warming is 2 to 3 times larger in the northern polar regions . . . Other model-predicted features are shifts of precipitation and soil moisture, retreat of polar snow and sea ice, and changes of large-scale circulation patterns.’ 2003 ‘ . . . a 2 °C warming target (which can still produce adverse climate impacts) requires non-CO2[89] emitting primary power in the 10 to 30 TW range by 2050.’ ‘The body of statistical evidence . . . now points towards a discernible human influence on global climate.’ ‘We present a preliminary analysis of a geoengineering option based on the intentional increase of ocean alkalinity to enhance marine storage of atmospheric CO2. Like all geoengineering techniques to limit climate change . . . .’ 6 ADVERTORIALS 1999 ‘Reasonable concerns about the buildup of greenhouse gases in the atmosphere and their effect on [91] earth’s climate have prompted policymakers to search for a response.’ 2003 ‘We humans are interacting with the geo-chemical systems of our planet on a global scale. The [93] concentration of carbon dioxide in the atmosphere has increased by a third from its preindustrial level, and the resulting change in the acidity of the upper ocean can be detected.’b a b 2002 ‘A major frustration to many is the all-too-apparent bias of IPCC to downplay the significance of [84] scientific uncertainty and gaps . . . .’ 2001 [85] 2003 [81] ‘A general statistical methodology . . . is proposed as a method for deciding whether or not anthropogenic influences are causing climate change.’ ‘Currently, our ability to forecast future climate is in question. Models are used to make projections of future climate, based on scenarios of future human activities and emissions, by simulating each link in the causal chain relating these scenarios to changes in climate. The estimation of the uncertainty of this causal chain remains an important scientific challenge.’ 1996 Title: ‘Global warming: who’s right? Facts about a debate that’s turned up more questions than answers.’ [88] ‘ . . . a multinational effort, under the auspices of the United Nations, is under way to cut the use of fossil fuels, based on the unproven theory that they affect the earth’s climate.’ 2008 ‘Nor are [the Oil and Natural Gas Industry Guidelines for Greenhouse Gas Reduction Projects] intended [90] to imply a direct connection between GHG emissions from the oil and natural gas industry and the phenomenon commonly referred to as climate change.’ 1997 ‘Let’s face it: The science of climate change is too uncertain to mandate a plan of action that could [92] plunge economies into turmoil . . . Scientists cannot predict with certainty if temperatures will increase, by how much and where changes will occur. We still don’t know what role man-made greenhouse gases might play in warming the planet . . . Let’s not rush to a decision at Kyoto. Climate change is complex; the science is not conclusive; the economics could be devastating.’ 1997 Title: ‘Climate change: a degree of uncertainty.’ [94] ‘ . . . there is a high degree of uncertainty over the timing and magnitude of the potential impacts that man-made emissions of greenhouse gases have on climate . . . To address the scientific uncertainty governments, universities and industry should form global research partnerships to fill in the knowledge gap, with the goal of achieving a consensus view on critical issues within a defined time frame . . . .’ Document filtered by our analysis as reasonable due to pre-1990 publication date. Advertorial is signed by Stanford University Professor Lynn Orr, then-director of Stanford’s Exxon-funded GCEP alliance, and bears the seal of Stanford University. See section S7, supplementary information, for details. Environ. Res. Lett. 12 (2017) 084019 Table 3. Example quotations (coding units) expressing (left) acknowledgment and (right) doubt that AGW is real and human-caused. For each document category, two examples are given: the first typifies a relatively ‘strong’ quotation, the second a relatively ‘mild’ one. Substantiating quotations for all documents are provided in section S7, supplementary information.